I feel a moron for this, but I locked myself out of my wallet (w/ about 2.5 BTC in it) today,
right after setting a passphrase. (I use bitcoin-qt.)

I tried all the obvious typing variants of the phrase, and then ran the Ruby script in this thread for an hour or so (basically through depth 2 of all 1-character substitutions into the passphrase I thought I was using).

Anyone have suggestions for next steps? I haven't "forgotten" anything about my passphrase; I even wrote it down "exactly" to store elsewhere for safekeeping. I don't have an unencrypted backup because I am a moron.

I run Ubuntu, but I am still nervous that my system might have been compromised somehow, although that's pretty unlikely. I didn't do anything in particular to secure the system (I don't encrypt my filesystem). I ran a couple of utilities to check for rootkits, but they didn't find anything suspicious.

So... somehow I must have mistyped the passphrase twice in a non-obvious way, which seems extraordinarily unlikely. I tried:
* Case inversion (caps lock)
* Adding punctuation and a space at the end
* All obvious variants for punctuation and capitalization in the passphrase
The script (I think) tried:
* All adjacent character swaps
* All 1-letter character changes
* Most 2-letter character changes

The form of the passphrase is (with capitalization and punctuation)
"Proper Name, Same Name; random word another Word"

Can anyone think of other good typing modifications to try?

If not, can anyone think what could be going on other than a strange repeated typo, or a malicious actor having installed (somehow!) a keylogger on my system and then changing the passphrase? Also I didn't have bitcoind installed at all until today, when I added it to run the Ruby script for brute-forcing the passphrase. Would it even be possible for someone else without physical access to my machine (which I'm fairly certain was safe) to have changed my passphrase with only bitcoin-qt installed on my system?

I've been using a version of bitcoin-qt installed via the Ubuntu package manner roughly 2 months ago (I think), and I have had some issues; once the block data got corrupted and I had to redownload the whole blockchain and start a new wallet, although this was before I owned any bitcoins, so I just moved on.  Could a buggy bitcoin installation have somehow caused my problem? Is it worth installing a new software wallet program and trying to import wallet.dat using that?